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From: BGB <cr88192@gmail.com>
Newsgroups: comp.arch
Subject: Re: Instruction Tracing
Date: Sun, 11 Aug 2024 02:41:01 -0500
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On 8/10/2024 6:20 PM, Lawrence D'Oliveiro wrote:
> On Sat, 10 Aug 2024 17:49:42 -0500, BGB wrote:
> 
>> Meanwhile, saw a video recently where someone had ported Doom to a 233
>> MHz PowerPC (running Windows NT4) machine and, its performance was not
>> good...
>>
>> Not obvious is what combination of factors conspired to cause Doom to
>> apparently run at single-digit framerates.
> 
> Windows NT never meant for games?

Windows GDI isn't fast, but it isn't usually *that* slow either.
WinQuake and Quake2 both used GDI to good effect.

If Windows GDI performance is seriously broken, this is a different 
issue from merely "not meant for games".


Normally, Doom is almost entirely self-contained, so there isn't likely 
that much area where OS APIs should effect all that much (apart from 
things like audio/graphics output, and checking for keyboard input).

Granted, that port using SDL could introduce some unknown variables 
here. AFAIK, "Chocolate Doom" is supposed to be a fairly direct port of 
the Doom engine (as opposed to heavily modified engines, like ZDoom).


Can note that my Doom port was based on Linuxdoom, but with some hacks 
to try to deal with Heretic and Hexen; before me noting that both 
Heretic and Hexen had source releases so I just ported these.

Doom generally runs fine at 50MHz, but can get a bit chunky at 16-20 MHz.

I am getting performance similar to that seen in the video, if I run 
Doom at roughly 12 MHz.


....